This study aims to thoroughly investigate the axial power peaking factors (PPF) within the low-enriched uranium (LEU) core of the Ghana Research Reactor-1 (GHARR-1). This study uses advanced simulation tools, like the...This study aims to thoroughly investigate the axial power peaking factors (PPF) within the low-enriched uranium (LEU) core of the Ghana Research Reactor-1 (GHARR-1). This study uses advanced simulation tools, like the MCNPX code for analysing neutron behavior and the PARET/ANL code for understanding power variations, to get a clearer picture of the reactor’s performance. The analysis covers the initial six years of GHARR-1’s operation and includes projections for its whole 60-year lifespan. We closely observed the patterns of both the highest and average PPFs at 21 axial nodes, with measurements taken every ten years. The findings of this study reveal important patterns in power distribution within the core, which are essential for improving the safety regulations and fuel management techniques of the reactor. We provide a meticulous approach, extensive data, and an analysis of the findings, highlighting the significance of continuous monitoring and analysis for proactive management of nuclear reactors. The findings of this study not only enhance our comprehension of nuclear reactor safety but also carry significant ramifications for sustainable energy progress in Ghana and the wider global context. Nuclear engineering is essential in tackling global concerns, such as the demand for clean and dependable energy sources. Research on optimising nuclear reactors, particularly in terms of safety and efficiency, is crucial for the ongoing advancement and acceptance of nuclear energy.展开更多
Advanced nuclear reactors offer safe, clean, and reliable energy at the global scale. The development of such devices relies heavily upon computational models, from the pre-conceptual stages through detailed design, l...Advanced nuclear reactors offer safe, clean, and reliable energy at the global scale. The development of such devices relies heavily upon computational models, from the pre-conceptual stages through detailed design, licensing, and operation. An integrated reactor modeling framework that enables seamless communication, coupling, automation, and continuous development brings significant new capabilities and efficiencies to the practice of reactor design. In such a system, key performance metrics （e.g., optimal fuel management, peak cladding temperature in design-basis accidents, levelized cost of electricity） can be explicitly linked to design inputs （e.g., assembly duct thickness, tolerances）, enabling an exceptional level of design consistency. Coupled with high-performance computing, thousands of integrated cases can be executed simultaneously to analyze the full system, perform complete sensitivity studies, and efficiently and robustly evaluate various design tradeoffs. TerraPower has developed such a tool-the Advanced Reactor Modeling Interface （ARMI） code system-and has deployed it to support the TerraPower Traveling Wave Reactor design and other innovative energy products currently under development. The ARMI code system employs pre-existing tools with strong pedigrees alongside many new physics and data management modules necessary for innovative design. Verification and validation against previous and new physical measurements, which remain an essential element of any sound design, are being carried out. This paper summarizes the integrated core engineering tools and practices in production at TerraPower.展开更多
One of the postponed problems of nuclear power (NP) is the problem of the management of long-lived radioactive waste (RAW), and, first of all, with minor actinides (MA), of which americium-241 is the most difficult. T...One of the postponed problems of nuclear power (NP) is the problem of the management of long-lived radioactive waste (RAW), and, first of all, with minor actinides (MA), of which americium-241 is the most difficult. The aim of this work is to study the efficiency of americium transmutation in a fast reactor with a heavy liquid metal coolant lead-bismuth eutectic alloy. The article presents the results of calculations of the transmutation of americium in the SVBR-100 reactor using standard uranium oxide fuel with the addition of americium-241. The obtained values of the rate of transmutation of americium are compared with similar values for the SVBR-100 reactors on MOX-fuel and in the BN-800 reactor.展开更多
Riser reactor is a key unit in the Fluid Catalytic Cracking (FCC), and it has important influences on increasing the yield coefficient of gas and oil. In this paper, the behaviors of gas-solid two-phase flow in the tr...Riser reactor is a key unit in the Fluid Catalytic Cracking (FCC), and it has important influences on increasing the yield coefficient of gas and oil. In this paper, the behaviors of gas-solid two-phase flow in the traditional y-type riser reactor are investigated by numerical simulation. The calculated particle concentration distribution is in good agreement with the experimental data, which verified the advanced models and calculating methods. The non-uniform distribution, such as core-annulus flow, may result in the unreasonable matching relationship of catalyst-to-oil ratio. An optimized riser with cuneal internals is proposed and the comparison of two different structures of riser reactor is presented. The comparison results show that the cuneal internals in the riser both can block effectively the slip down of the particles near wall region and weaken core-annulus flow structure due to the redistribution of particles. The results also prove that the particle concentration distribution becomes uniform along the axial and radial direction in the optimized riser by adding cuneal internals, which would be benefits for the catalytic cracking reactions.展开更多
Numerical simulations of a representative test of welding process are presented in this paper. A French vessel steel, which involves metallurgical phase transformations in solid state is considered in this work. The a...Numerical simulations of a representative test of welding process are presented in this paper. A French vessel steel, which involves metallurgical phase transformations in solid state is considered in this work. The aim is to validate the thermal-metallurgical-mechanical models taking into account the metallurgical transformations in the finite element codes Sysweld (Framasoft) and Code Aster (EDF). The test is performed on a thin disc submitted to a thermal cycle loading by means of a CO2 laser beam, which leads to metallurgical phase transformations. The thermal, metallurgical and mechanical numerical results have been compared to the experimental results (temperatures, sizes of transformed zones, displacements and residual stresses and strains). The main objective of the numerical analysis is to have some results which enable to give some indications on the ability of the numerical codes to describe the observed phenomena. For that, it is necessary to simulate accurately the thermo-metallurgical history. The comparison of experimental results with the numerical ones leads to some interesting orientations related to the capacities of the considered models to describe the observed phenomena.展开更多
Tight oil resources are abundant in the world.It is very important to strengthen the research on the development theory and technology of tight oil reservoirs for ensuring national energy security.Natural gas huff-n-p...Tight oil resources are abundant in the world.It is very important to strengthen the research on the development theory and technology of tight oil reservoirs for ensuring national energy security.Natural gas huff-n-puff can effectively improve the oil recovery of tight oil reservoirs.However,the pore-scale oil production characteristics and the mechanisms of natural gas huff-n-puff in matrix-fracture cores are poorly understood.The influence degree of important factors on oil recovery is not clear and the interactions between factors are rarely considered.In this paper,the oil production characteristics and mechanisms of natural gas huff-n-puff in tight cores with different fracture lengths were quantitatively analyzed by combining nuclear magnetic resonance(NMR)with numerical simulation technology.The influencing factors and their interactions were evaluated by the response surface method(RSM).The results show that tight cores mainly consist of medium pores(0.1–1μm)and small pores(0.01–0.1μm).The fracture mainly increases the proportion of macro-pores(1–10μm)and medium pores.In the natural gas huff-n-puff process,crude oil from macro-pores(1–10μm)and medium pores is mainly developed,and the contribution percentage of crude oil in medium pores to oil recovery is the largest,up to 98.28%.The position of gas–oil contact(GOC)moves deeper as the number of huff-n-puff cycles increases.The contents of CH_(4) and CO_(2) in the oil phase remain at a high level within the GOC,while between the GOC and the component sweep front,the contents of CH_(4) and CO_(2) in the oil phase decrease with the increase in dimensionless distance.The gas component sweep volume is increasing with the increase in fracture length.Moreover,the injected natural gas mainly extracts C_(3)–C_(10) components from crude oil.The reduction law of crude oil viscosity is consistent with the migration laws of CH_(4) components along the path.Compared with soaking time and gas diffusion coefficient,the injection pressure is the most significant factor underlying the recovery of natural gas huff-n-puff in tight cores.Besides the influence of single-factor,the interaction effects of gas injection pressure and diffusion also should be considered to determine the huff-n-puff parameters in the field implementation of natural gas huff-n-puff in tight reservoirs after fracturing.展开更多
文摘This study aims to thoroughly investigate the axial power peaking factors (PPF) within the low-enriched uranium (LEU) core of the Ghana Research Reactor-1 (GHARR-1). This study uses advanced simulation tools, like the MCNPX code for analysing neutron behavior and the PARET/ANL code for understanding power variations, to get a clearer picture of the reactor’s performance. The analysis covers the initial six years of GHARR-1’s operation and includes projections for its whole 60-year lifespan. We closely observed the patterns of both the highest and average PPFs at 21 axial nodes, with measurements taken every ten years. The findings of this study reveal important patterns in power distribution within the core, which are essential for improving the safety regulations and fuel management techniques of the reactor. We provide a meticulous approach, extensive data, and an analysis of the findings, highlighting the significance of continuous monitoring and analysis for proactive management of nuclear reactors. The findings of this study not only enhance our comprehension of nuclear reactor safety but also carry significant ramifications for sustainable energy progress in Ghana and the wider global context. Nuclear engineering is essential in tackling global concerns, such as the demand for clean and dependable energy sources. Research on optimising nuclear reactors, particularly in terms of safety and efficiency, is crucial for the ongoing advancement and acceptance of nuclear energy.
文摘Advanced nuclear reactors offer safe, clean, and reliable energy at the global scale. The development of such devices relies heavily upon computational models, from the pre-conceptual stages through detailed design, licensing, and operation. An integrated reactor modeling framework that enables seamless communication, coupling, automation, and continuous development brings significant new capabilities and efficiencies to the practice of reactor design. In such a system, key performance metrics （e.g., optimal fuel management, peak cladding temperature in design-basis accidents, levelized cost of electricity） can be explicitly linked to design inputs （e.g., assembly duct thickness, tolerances）, enabling an exceptional level of design consistency. Coupled with high-performance computing, thousands of integrated cases can be executed simultaneously to analyze the full system, perform complete sensitivity studies, and efficiently and robustly evaluate various design tradeoffs. TerraPower has developed such a tool-the Advanced Reactor Modeling Interface （ARMI） code system-and has deployed it to support the TerraPower Traveling Wave Reactor design and other innovative energy products currently under development. The ARMI code system employs pre-existing tools with strong pedigrees alongside many new physics and data management modules necessary for innovative design. Verification and validation against previous and new physical measurements, which remain an essential element of any sound design, are being carried out. This paper summarizes the integrated core engineering tools and practices in production at TerraPower.
文摘One of the postponed problems of nuclear power (NP) is the problem of the management of long-lived radioactive waste (RAW), and, first of all, with minor actinides (MA), of which americium-241 is the most difficult. The aim of this work is to study the efficiency of americium transmutation in a fast reactor with a heavy liquid metal coolant lead-bismuth eutectic alloy. The article presents the results of calculations of the transmutation of americium in the SVBR-100 reactor using standard uranium oxide fuel with the addition of americium-241. The obtained values of the rate of transmutation of americium are compared with similar values for the SVBR-100 reactors on MOX-fuel and in the BN-800 reactor.
文摘Riser reactor is a key unit in the Fluid Catalytic Cracking (FCC), and it has important influences on increasing the yield coefficient of gas and oil. In this paper, the behaviors of gas-solid two-phase flow in the traditional y-type riser reactor are investigated by numerical simulation. The calculated particle concentration distribution is in good agreement with the experimental data, which verified the advanced models and calculating methods. The non-uniform distribution, such as core-annulus flow, may result in the unreasonable matching relationship of catalyst-to-oil ratio. An optimized riser with cuneal internals is proposed and the comparison of two different structures of riser reactor is presented. The comparison results show that the cuneal internals in the riser both can block effectively the slip down of the particles near wall region and weaken core-annulus flow structure due to the redistribution of particles. The results also prove that the particle concentration distribution becomes uniform along the axial and radial direction in the optimized riser by adding cuneal internals, which would be benefits for the catalytic cracking reactions.
文摘Numerical simulations of a representative test of welding process are presented in this paper. A French vessel steel, which involves metallurgical phase transformations in solid state is considered in this work. The aim is to validate the thermal-metallurgical-mechanical models taking into account the metallurgical transformations in the finite element codes Sysweld (Framasoft) and Code Aster (EDF). The test is performed on a thin disc submitted to a thermal cycle loading by means of a CO2 laser beam, which leads to metallurgical phase transformations. The thermal, metallurgical and mechanical numerical results have been compared to the experimental results (temperatures, sizes of transformed zones, displacements and residual stresses and strains). The main objective of the numerical analysis is to have some results which enable to give some indications on the ability of the numerical codes to describe the observed phenomena. For that, it is necessary to simulate accurately the thermo-metallurgical history. The comparison of experimental results with the numerical ones leads to some interesting orientations related to the capacities of the considered models to describe the observed phenomena.
基金supported by the National Natural Science Foundation of China(Grant No.U22B6004,51974341,51904324)the Fundamental Research Funds for the Central Universities(No.20CX06070A)the Science and Technology Support Plan for Youth Innovation of University in Shandong Province(Grant No.2019KJH002).
文摘Tight oil resources are abundant in the world.It is very important to strengthen the research on the development theory and technology of tight oil reservoirs for ensuring national energy security.Natural gas huff-n-puff can effectively improve the oil recovery of tight oil reservoirs.However,the pore-scale oil production characteristics and the mechanisms of natural gas huff-n-puff in matrix-fracture cores are poorly understood.The influence degree of important factors on oil recovery is not clear and the interactions between factors are rarely considered.In this paper,the oil production characteristics and mechanisms of natural gas huff-n-puff in tight cores with different fracture lengths were quantitatively analyzed by combining nuclear magnetic resonance(NMR)with numerical simulation technology.The influencing factors and their interactions were evaluated by the response surface method(RSM).The results show that tight cores mainly consist of medium pores(0.1–1μm)and small pores(0.01–0.1μm).The fracture mainly increases the proportion of macro-pores(1–10μm)and medium pores.In the natural gas huff-n-puff process,crude oil from macro-pores(1–10μm)and medium pores is mainly developed,and the contribution percentage of crude oil in medium pores to oil recovery is the largest,up to 98.28%.The position of gas–oil contact(GOC)moves deeper as the number of huff-n-puff cycles increases.The contents of CH_(4) and CO_(2) in the oil phase remain at a high level within the GOC,while between the GOC and the component sweep front,the contents of CH_(4) and CO_(2) in the oil phase decrease with the increase in dimensionless distance.The gas component sweep volume is increasing with the increase in fracture length.Moreover,the injected natural gas mainly extracts C_(3)–C_(10) components from crude oil.The reduction law of crude oil viscosity is consistent with the migration laws of CH_(4) components along the path.Compared with soaking time and gas diffusion coefficient,the injection pressure is the most significant factor underlying the recovery of natural gas huff-n-puff in tight cores.Besides the influence of single-factor,the interaction effects of gas injection pressure and diffusion also should be considered to determine the huff-n-puff parameters in the field implementation of natural gas huff-n-puff in tight reservoirs after fracturing.
